C-8 Sensory Dermatome Surface Anatomy

Location

The C8 nerve root can be evaluated by testing sensation on the volar aspect of the little finger.

Significance

Loss of sensation should be correlated to the motor exam; in this case finger flexion.
http://www.orthopaedia.com/display/Main/C-8+Motor–Flexor+Digitorum+Superficialis

Sensory loss involving a more diffuse area, overlapping several dermatomes suggests a peripheral nerve injury.

The most sensitive way of assessing sensory loss is using two-point discrimination.